1. Field of the Invention
This invention relates to an improvement in a dampening system, particularly of the type employed in heating operations. More particularly, this invention relates to an improvement in a dampening system whereby the vane of the dampener is positively maintained in a closed position when the system is not being used for heat generation, but is returned to an open position upon commencement of a heating operation. This invention is particularly directed to a dampening means in which the vane is held in a closed position by actuation of an electric motor, which electric motor is deenergized in response to a thermostat, whereby de-energization of the motor causes a heating cycle to commence after a short time delay.
2. Discussion Of The Prior Art
Numerous dampening systems for use in heat and smoke stacks have been heretofore proposed. Such systems are typified by those disclosed in U.S. Pat. Nos. 2,977,437, 3,273,625, and 3,580,238. In U.S. Pat. No. 3,580,238, there is disclosed a system in which the vane of the dampening means is opened upon the introduction of power to a solenoid. A major disadvantage of this system is found particularly in systems having manually operated gas valves. Should there be a power failure combustion could still be made to take place in such a system while the vane remains shut, i.e., the electric power would not open the vane, and thus, combustion would build up within an otherwise closed system. Such a system represents a serious saftey hazard. Additionally, the system employs Teflon or other thermoplastic bearings which will not endure the temperatures normally generated in the stack. Other materials such as silicone rubber are employed in the form of pads to provide both an escape path for pilot combustion products and for cushioning the noise of the sudden vane stoppage at the end of its stroke. Silicone rubber, unfortunately, will not withstand temperatures higher than 575.degree. F., temperatures which are readily exceeded in a gas or oil fired heating system.
U.S. Pat. No. 3,273,675 similarly employs power to open the vane upon commencement of a heating cycle. It also suffers from the same disadvantages inherent in the apparatus of U.S. Pat. No. 3,580,238. Therein, there is proposed to employ a uni-directional double oscillator motor. Unfortunately, the use of such an oscillating device is accompanied with noise which resounds throughout the heating system, particularly if the heating system is one which contains large surfaces of sheet metal, e.g., as found in hot air heating systems.
It has, therefore, become desirable to provide an improved damping system which is simply constructed, does not require the use of substances which will degrade at the temperatures generated in the system, is virtually noise-free, and, most importantly, insures that should there be a power failure, the vane of the dampener will be automatically disposed in an open position. These and other objects are accomplished by the invention as will appear from the disclosure below.